Production of alkenones

ABSTRACT

ALKENONES WHOSE OLEFINIC DOUBLE BOND IS IN THE $,E-POSITION OR Y,&amp;-POSITION TO THE KETO GROUP, ARE PREPARED BY REACTION OF AN OLEFIN WITH A B-HYDROXYKETONE IN THE LIQUID PHASE OR IN A SINGLE REACTION STAGE BY REACTION OF AN OLEFIN WITH FORMALDEHYDE OR A COMPOUND YIELDING FORMALDEHYDE AND AN ALIPHAIC KETONE IN THE LIQUID PHASE. ALKENONES ARE INTERMEDIATES FOR THE PRODUCTION OF PERFUMES AND VITAMINS.

United States Patent ()ifice 3,819,713 Patented June 25, 1974 US. Cl.260-593 R Claims ABSTRACT OF THE DISCLOSURE Alkenones whose olefinicdouble bond is in the 5,e-POSltion or t-position to the keto group, areprepared by reaction of an olefin with a fl-hydroxyketone in the liquidphase or in a single reaction stage by reaction of an olefin withformaldehyde or a compound yielding formaldehyde and an aliphatic ketonein the liquid phase. Alkenones are intermediates for the production ofperfumes and vitamins.

This application is a continuation-in-part of our application Ser. No.660,195, filed Aug. 14, 1967, now abandoned.

The invention relates to a new method for the production of alkenones ofthe general formulae Ia and Ib CHRI=CR2-CHR3CHZ-CHR4COCHQR5 (Ia) CH RCR=CR CH CHR COCH R (Ib) where each of the R to R substituents denoteshydrogen or alkyl of 1 to 4 carbon atoms.

It is known that butanol-(l)-one-(3) can be prepared by reaction ofacetone with formaldehyde. Moreover the addition of isobutylene toformaldehyde to form Z-methylbuten-(1)-ol-(4) is known. It is furtherknown that 2- methylheptanol-(2)-one-(6) can be prepared from 3-methylbuten-(1)-ol-(3) and acetone at elevated temperatures usingperoxide catalysts.

5,6-UI1S3tlJIEltCd ketones of the type Ia have been prepared by additionof olefins having the structure to a e-unsaturated ketones of the typebut this method is uneconomical because it requires the preparation ofthe unsaturated ketones (German Patent 973,089), which have to besynthesized, inter alia, from ketones and formaldehyde at elevatedtemperatures in the vapor phase in the presence of dehydration catalysts(French Pat. 870,204).

Finally methylene addition according to Carrol is known by which forexample 2-methylhepten-(2)-one-( 6) is obtained from3-methylbuten-(1)-ol-(3) and acetoacetic ester at 150 to 250 C. in thepresence of alkaline catalysts.

It is an object of this invention to provide a simple method ofproducing alkenones Ia and 1b in which inexpensive starting materialsare used, in which the use of catalysts is not necessary and which maybe carried out not only batchwise but also continuously. It is a furtherobject of the invention to provide a method for the production ofalkenones starting from a-ketone, formaldehyde and an olefin which iscarried out in a single stage.

These and other objects are achieved by reaction of an olefin of thegeneral formula II CH R CR =CHR with (a) a fl-hydroxyketone having thegeneral formula III HOCH CHR COCH R (III) (b) a ketone of the generalformula IV CH R CO-CH -R (IV) and formaldehyde or a compound yieldingformaldehyde at a temperature of from 100 to 400 C. and under theautogenous pressure up to about 1,000 atmospheres gauge in the liquidphase.

When isobutylene is reacted with (a) butanol-(4)-one-(2)-or (b)formaldehyde and acetone,

methylheptenone is obtained according to the equation:

The relative proportions in which the two isomers are. formed depend onthe reaction conditions. At high temperatures major amounts ofheptene-(2) compounds are formed, although the formation of primaryolefin is always favored.

Of the olefins having the formula:

those are particularly suitable which have 3 to 12 carbon atoms. Methylis preferred as the alkyl substituent R R or R Examples of suitableolefins are propylene, butene- (2), hexenes, octenes and particularlyisobutylene and 2- methylbutene- (2) r It is also possible to producethe olefin during the reaction by dehydration of the appropriatealcohol. If the alcohol is thermally dehydrated under the reactionconditions, as is the case with tertiary alcohols, the use ofdehydration catalysts may be dispensed with. In many cases it is howeveradvantageous to use conventional dehydration catalysts, e.g. aluminumoxide, silica gel, Lewis acids, mineral acids and phosphates of metalsof Group :II of the Periodic System.

Suitable alcohols include propanol-(2), butanols, hexanols andparticularly tertiary alcohols, such as tert-butamay be used. An aqueoussolution of formaldehyde is often employed. Examples of other compoundsare trioxane, paraformaldehyde, hydrated polyformaldehyde andpolyformaldehydes whose terminal hydroxyl groups have been etherified oresterified. The polymers have the general formula:

in which n in general denotes one of the integers from 3 to 100,particularly from 3 to 20. The polymers may be cyclic (11 preferablybeing 3 or 4) or open-chain in constitution and the chain ends of thepolymer molecule are usually satisfied by the groupingH OH, H OR or HOCOR, R being usually a lower alkyl radical having one to four carbonatoms.

Examples of preferred ketones of formula IV are those having 3 to 12carbon atoms. The preferred alkyl radical for R or R is the methylgroup. Acetone, butanone and diethylketone are very well suited.

The olefin of formula II and the fl-hydroxyketone of formula III areusually employed in the molar ratio of from 0.1:1 to :1, preferably from0.2:1 to 5:1.

The components (a) olefin of formula II, (b) formaldehyde or anequivalent amount of a compound yielding formaldehyde and (c) ketone offormula IV are in general used in the molar ratio of from 10:01 :1 to0.02102: 1, particularly from 2:02:l to 0220.2: 1. The ratio of ketoneto olefin is not critical. The reactants may be used with similarsuccess in equimolar or nonequimolar amounts and it is immaterial whichof the reactants is used in excess. As regards the amount offormaldehyde, the best results are usually obtained if the equimolaramount is not exceeded.

The reaction is carreid out in the liquid phase at elevated temperature,generally in the temperature range from 100 to 400 C., particularly from200 to 350 C., preferably from 200 to 280 C. The reaction may be carriedout at atmospheric pressure, but it is preferable to usesuperatmospheric pressure, for example the vapor pressure of thereactants at the reaction temperature, for example up to 1,000atmospheres gauge, particularly from 50 to 500 atmospheres gauge.

The residence time may vary within wide limits and is highly dependenton the reaction temperature, the pressure and the molar ratio used.Residence times of from ten to one thousand minutes are preferred.

The reaction may be carried out without solvents, but it is preferred touse solvents or diluents, such as saturated aliphatic or aromatichydrocarbons, alcohols, ethers or water. Examples of suitable solventsare hexane, octane, benzene, toluene, diethyl ether, tetrahydrofuran,dioxane, methanol and propanol or the reaction components. Mixtures ofsolvents may also be used. The solvents or diluents are in general usedin 0.1 to 10 times the weight of the reactants.

When water is used as the solvent, the preferred pH value is from 5 to8; appropriate amounts of inert buffer substances are advantageouslyadded to keep a specific pH value constant during the whole reactionperiod.

Since polymers of formaldehyde (trioxane, paraformaldehyde,polyformaldehyde) sometimes react more slowly than free formaldehyde, itis sometimes advantageous to use a small amount of a catalyst whichcatalyzes the depolymerization of the polymers. Aliphatichalohydrocarbons, such as methylene chloride, chloroform or carbontetrachloride are particularly suitable substances for this purpose. Thecatalyst is used in general in an amount of 5 to 50% by weight, based onthe aldehyde polymer.

The reaction may be carried out batchwise or continuously. Working up ofthe reaction mixture is carried out in the conventional way by physicalor chemical separation methods. The reaction mixture is usuallydistilled, the unreacted starting material being recovered and ifdesired returned to the reaction.

The alkenones Ia and Ib obtained are valuable intermediates for organicsynthesis, particularly for the production of perfumes and vitamins.Methylheptenones, for example, are starting materials for the synthesisof pseudoionone and vitamin A.

The invention is illustrated by the following Examples in which theparts specified are parts by weight unless otherwise stated.

EXAMPLE 1 An autoclave filled with V2A packing material and having auseful capacity of two liters is charged continuously at 280 C. and 200atmospheres gauge with a mixture f 600 parts of butanol-(4)-one(2)(technical grade; purity 70%) and 600 parts of isobutylene per hour. Thereaction mixture obtained every hour is distilled and the followingfractions are obtained on an average:

400 parts of unreacted isobutylene 200 parts of volatile crackedproducts (acetone and water) 250 parts of a methylheptenone mixture,b.p. to

C. (100 mm.), consisting essentially of Z-methylhepten- 1 )-one- 6)parts of higher-boiling products, b.p. 100 to C.

200 parts residue.

EXAMPLE 2 A mixture of 200 parts of butanol-(4)-one-(2) (technicalgrade; purity 70%) and 250 parts of isobutylene is heated in anautoclave for two hours at 270 C. the contents of the vessel are rapidlycooled and worked up by distillation and the unreacted isobutylene isevaporated. 222 parts of residue is obtained which on fractionaldistillation yields 107 parts of 2-methylhepten-(l)-one-(6).

EXAMPLE 3 A mixture of 118 parts of acetone, 118 parts of isobutyleneand 100 parts of 40% by weight aqueous formaldehyde solution is heatedin an autoclave at 250 C. for three hours. The contents of the autoclaveare then cooled rapidly and worked up by distillation. The followingfractions are obtained:

86 parts of isobutylene 100 parts of acetone 20 parts of2-methylhepten-(l)-one-(6) 10 parts of a fraction of the boilin range 80to 100 C. (15 mm.) and 30 parts of residue.

EXAMPLE 4 An autoclave provided with an overflow and having a usefulcapacity of 2.5 parts by volume is charged per hour at 280 C. and at 200atmospheres gauge with a mixture of 685 parts of acetone, 590 parts ofisobutylene and 183 parts of 37% by weight aqueous formaldehydesolution. The reaction mixture obtained in the course of twelve hours isdistilled. 5,600 parts of isobutylene and 7,050 parts of acetone arerecovered. The aqueous phase of the remaining mixture is separated andthe organic phase is distilled under subatmospheric pressure. 2,600parts of distillate having a boiling point of 60 to 100 C. at 100 mm. isobtained which contains 75% of Z-methylhepten- (l)-one-(6) and2-methylhepten-(2)-one-(6), and 300 parts of residue.

EXAMPLE 5 A mixture of 200 parts of acetone, 50 parts of trioxane and177 parts of isobutylene is heated in a stirred autoclave for one hourat 290 C. The contents of the autoclave are cooled rapidly and worked upby distillation. The following fractions are obtained:

130 parts of isobutylene 84 parts of acetone 30 parts of a mixture oftrioxane and water 86 parts of 2-methylhepten-(l)-one-(6), b.p. 69 to 70C. (20 mm.)

36 parts of a mixture of products of the boiling range 80 to 120 C. (0.2mm.) and 56 parts of residue.

EXAMPLE 6 A mixture of 200 parts of acetone, 50 parts of a mixture offormaldehyde hydrate polymers having a boiling range of 60 to 90 C. (20mm.) and 177 parts of isobutylene is heated at 280 C. in a stirredautoclave for one hour. The contents of the autoclave are then cooledrapidly and worked up by distillation. 84 parts ofZ-methylhepten-(1)-one-(6) and 17 parts of residue are obtained as wellas unchanged isobutylene and acetone.

EXAMPLE 7 A mixture of 1200 parts of acetone, 50 parts of formaldehydehydrate polymer mixture having a boiling range of 90 to 130 C. (20 mm.)and 177 parts of isobutylene is heated in an autoclave for one hour at285 C. The contents of the autoclave are then cooled and worked up bydistillation. 77 parts of 2-methylhepten-(1)-one-(6) and 17 parts ofresidue are obtained in addition to un reacted starting materials.

EXAMPLE 8 An autoclave having a capacity of 1 part by volume is chargedper hour at 300 C. and 300 atmospheres gauge with a mixture of 360 partsof acetone, 45 parts of aqueous 37% by weight formaldehyde solution and330 parts of Z-methylbutene-(Z). The reaction solution obtained isworked up by distillation. 50 parts of 2,3-dimethylhepten- (1)-one-(6)having a boiling point of 115 C. (100 mm.) is obtained from the reactionmixture obtained in one hour.

EXAMPLE 9 The procedure of Example 6 is followed but 300 parts ofpropylene is used instead of Z-methyIbutene-(Z). By working up thereaction product obtained in one hour, 60 parts of hepten-(1)-one(6)having a boiling point of 78 to 82 C. (100 mm.) may be obtained.

EXAMPLE 10 mula II CH R CR =CHR (II) wherein R R and R have the meaningsdefined above, with a ketone of the formula IV CH R*--COCH R (IV)wherein R and R have the meaning defined above and also withformaldehyde as a coreactant.

2. A process as claimed in claim 1 wherein the formaldehyde coreactedwith the ketone IV is supplied by a compound selected from the groupconsisting of a hydrate, an acetal, an oligomer and a polymer offormaldehyde.

3. A process as claimed in claim 1 wherein the olefin II, theformaldehyde and the ketone IV are used as coreactants in a molar ratioof from 10:0.1:1 to 0.02:0.2:1.

4. A process as claimed in claim 1 for producing alkenones of theformulae by reacting isobutylene with acetone and formaldehyde.

5. A process as claimed in claim 4 carried out at a temperature of 200C. to 350 C., a pressure of about to 500 atmospheres gauge and a molarratio of isbutylene:formaldehyderacetone of from 1010.1 :1 to0.02:0.2z1.

References Cited UNITED STATES PATENTS 989,993 4/1911 Merling et al.260594 3,422,148 1/1969 Wellner et al 260593 R 2,246,037 6/1941Gallagher et a1. 260593 R 2,055,456 9/1936 Eichwald 260485 2,230,005 1/1941 Moser 260537 FOREIGN PATENTS 973,089 12/1959 Germany 260593 R OTHERREFERENCES Walker, Formaldehyde, p. 295 (third edition) (1968).

DANIEL D. HORWITZ, Primary Examiner I [SEAL].

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 3,819, 713 DATED June 25, 19 74 INVENTOR(S) Horst Palmer, eta1 it is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown eiow;

In the Heading, insert between lines 9 and 10, Claims priority,application Germany, May 11, 1966, B87070; July 16, 1966, B88034; August27, 1966, B88674" Signed and Scaled this Twenty-fourth Day of August1976 A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufPaiemsand Trademarks I [SEAL].

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 3,819, 713 DATED June 25, 19 74 INVENTOR(S) Horst Palmer, eta1 it is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown eiow;

In the Heading, insert between lines 9 and 10, Claims priority,application Germany, May 11, 1966, B87070; July 16, 1966, B88034; August27, 1966, B88674" Signed and Scaled this Twenty-fourth Day of August1976 A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufPaiemsand Trademarks

